Field of the Invention
This invention relates to a driver assist device for an industrial truck and to an industrial truck with a driver assist device. In particular, the invention relates to a driver assist device for an industrial truck having at least one steered wheel at the rear end of the truck, which driver assist device, when located on the industrial truck, projects a lighting effect on the roadway.
Technical Considerations
It is known that a wide range of vehicles, e.g. buses, motor homes and trucks, can be equipped with a camera system to avoid collisions with obstacles in difficult driving situations and in situations where the driver's vision is impeded, and to give the driver an estimation of the path of the vehicle which is difficult or even impossible to obtain by means of mirrors or a direct line of sight. The use of camera systems on industrial trucks, in particular on counterbalance fork-lift trucks, is also known. DE 10 2007 063 226 A1 describes the superimposition of the potential path of the vehicle, as a function of a steering angle, on the display of a camera image to indicate whether, at a selected steering angle, a potential obstacle is located in the path of the vehicle.
One disadvantage of this method is that the display of the camera does not provide a three-dimensional impression but rather only a significantly smaller image of the roadway. This situation requires a high level of attention on the part of the driver to ascertain whether or not there are obstacles in the path of the vehicle.
Industrial trucks that are in the form of counterbalance fork-lift trucks having a lifting mast on the front end are frequently constructed so that the vehicle is driven by means of a forward axle with wheels that are not steered. On the rear of the counterbalance fork-lift truck, there is a counterbalance located with the largest possible lever arm with respect to the lifting mast. Below the counterbalance there are one or two steered wheels. The steered wheels are generally not drive wheels. In an alternative example, in particular for three-wheel fork-lift trucks, the function of steering and optionally propulsion are combined in a single wheel which is located underneath the counterbalance. Industrial trucks which are in the form of warehouse materials handling equipment such as pallet trucks, reach trucks, order pickers, in particular horizontal order pickers or vertical order pickers, swing fork-lift trucks and high-level stackers, are steered by one or more wheels on the rear end of the truck. In all these cases, however, the steered wheels have very large turning angles to achieve the smallest possible turning circle and to make possible a 90° turn even in narrow aisles of warehouse shelves, to enable a load handling device such as a load fork, for example, to be oriented correctly with respect to a shelf space. Steering angles of up to approximately 90° are conventional, corresponding to a position at a right angle to the longitudinal direction of the vehicle. That makes it possible to turn the counterbalance fork-lift truck essentially around the front axle. Both the location of the steered wheels in the rear end and the large turning angle of the wheels means that when the vehicle is traveling at the full steering angle, the rear end of the industrial truck swings out very sharply. This movement can result in damage to adjacent structures, loads or shelves, which can also happen if the driver miscalculates or is unaware of the curve of the path or the path of the periphery of the vehicle and collisions can occur. There are also potential risks to people in the area who are standing behind and to one side in the vicinity of an industrial truck of this type.
DE 10 2006 002 960 A1 describes an industrial truck with an optical warning device in which a lighting effect that points in the direction of travel is projected onto the roadway to warn people in the vicinity of the approach of the industrial truck. One disadvantage of this system is that it does not take into consideration the risks caused by the lateral swinging out of an industrial truck as it travels around a curve.
Therefore, it is an object of the invention to provide a driver assist device as well as an industrial truck, in particular a counterbalance fork-lift truck, with which it is possible to easily and quickly recognize the movement of the industrial truck as it travels on a curved path and thereby to eliminate the disadvantages described above.